Heating pad thermostat



Aug. 31, I I

L. M. HOWARD HEATING PAD THERMOSTAT' Filed Nov. 10, 1941 Patented Aug.31, 1943 5 PATENT OFFICE HEATING ran THERMOSTAT Lawrence M. Howard, St.Louis, Mo., assignor to Knapp-Monarch Company, St. Louis, Mo., acorporation of Missouri Application November 10, 1941, Serial No.418,458

' 7 Claims: 01. 200-138) My present invention relates to a thermostatparticularly designed for heating pads or the like. In connection with aheating pad it is desirable to have a relatively small thermostat so asto reduce the bulkiness, of the pad where thethermostat is'located. Itis necessary, however, to provide the necessary space for warping of thebimetal element of the thermostat and longitudinal movement of anadjusting screw It is accordingly an object of my invention to provide asimple and inexpensive thermostat which may be made-small in size yetutilizes a casing of insulating material instead of metal, as

usual.

Another object is to provide the casing and the elements therein soarranged that the casing is wider than it is high, its width permittingthe necessary space for operation of the bimetal element and adjustmentof the adjusting screw, while, at the same time, compactness of thestructure is obtained. v V

A further object is to provide a casing which is open on its side, andthe open side is closed by a cover that needs no fastening means otherthan a wrapping of stringer the like, which also retains the ends oflead wires to the casing against being pulled out of the casing.

With these and other objects in view, my invention consists in theconstruction, arrangement and combination of thevarious parts of mydevice whereby the objects contemplated are attained, asv hereinaftermore fully set forth, pointed out in myv claims and illustrated in theaccompanying drawing, wherein:

Figure 1 is aperspective View of a'thermostat embodying my invention; l1

Figure 2 is a side view thereof lo'oking'into the interior, with thecover removed;

Figure 3 is a sectionalview on the line 3--3 of Figure 2 showing thecover in position'and the thermostat fully assembled; and

Figure 4 is an exploded perspective view of the casing and cover and thethree metallic elements within the casing which.v constitute theessential parts of my thermostat;

On the accompanying drawing I have used the reference character toindicate a casing. The casing C has a side wall I0 opposite an open sidethereof. Within the casing C I provide a terminal bar [2, a bimetalelement l3 and a second terminal bar M. For closing the open side of thecasing C I provide a cover 15.

The first terminal bar I2 is secured to the side I 0 of the casing C bya rivet [6. The bar substantially fits in the casing between the upperand lower walls thereof to prevent it from turning on the rivet l6.Anadjustable contact I"! is screw-threaded in an opening I8 of the bar[2 adjacent one end thereof, and the casing side H! has an opening I! inwhich the head of the contact screw I1 is countersunk so as to preventaccidental contact of the user therewith.

The bimetal element I3 carries a contact 20 to cooperate with a contact[9 of the screw H. The bimetal element I3 is mounted on an elevated sideportion 10 of the casing side ill by means of a rivet 2|. The rivet 2|also supports the terminal bar it in position and affords an electricalconnection between it and the bimetal element l3.

A lead wire 22 extends through an opening 22 of the casing side [0 andthrough a perforation 23 in the terminal bar 12. The extending end isthen soldered to the terminal bar. A second lead wire 24 extends throughan opening 24 in the cover [5 and through a perforation 25 in the secondterminal bar it. The end of the lead wire 24 is then soldered to theterminal bar.

The ends of the open side of the casing C are rabbeted, as indicated at28, whereas the cover [5 is provided with notches 21. The notches 21leave enlarged ends 29 on the cover to fit in the rabbets 28, thenotches themselves fitting projections 30 of the casing C, thuspositively positioning the cover l5 with relation to the casing C.

During assembly the lead wire 24 is threaded through the opening 24 ofthe cover 15, and after the cover is in its proper position a wrapping26 of cord (preferably asbestos cord) is used to retain the cover on thecasing and to anchor the ends of the lead wires where they extend intothe thermostat, thus preventing their soldered connections from beingpulled loose from the terminal bars 12 and I4.

From the foregoing disclosure it is obvious that I have designed arelatively compact arrangement of parts, making it possible to providean insulating casing for the thermostat, having the necessary strengthto prevent crushing, and serving as a protection against shocks thatmight occur where a metallic casing for the thermostat is used. Theparts are few and simple to construct, and the assembly problem has beenre duced to a minimum of operations and time required.

.. Some changes may be made in the construction ;.and arrangement of theparts of my device without departing from the real spirit and purpose ofmy invention, and it is my intention to cover by my claims any modifiedforms of structure or a relatively narrow casing of insulating materialhaving an open side, a terminal bar in said casing ad acent the oppositeside thereof, a lead wire through said opposite side and connected withsaid terminal bar, an adjustable contact carried by said terminal bar,said opposite side of said casing having an elevated portion adjacentone end of said terminal bar, a bimetal element secured to said elevatedportion and having a contact to cooperate with said first mentionedcontact, a second terminal bar connected with the portion of saidbimetal element on said elevated portion, a second lead wire connectedtherewith, said terminal bars and said bimetal elements substantiallyfilling said casing widthwise, a cover for the open side of said casing,means for positioning said cover relative to said casing, and a singlemeans surrounding said casing and cover and the portions of said leadwires adjacent said casing and cover to retain the cover on the casingand secure the lead wires against pulling on said terminal bars.

2. In a thermostat for heating pads or the like, a casing of insulationhaving an open side, a terminal bar in said casing attached against theopposite side thereof, said opposite side having a hole therethrough,said terminal bar having a hole in alinement with said hole of saidcasing, a lead wire through said hole of said casing and through saidhole of said terminal bar and soidered in the latter hole, an adjustablecontact carried by said terminal bar, said opposite wall of said casinghaving a second hole partially receiving the portion of said adjustingscrew outside of said terminal bar, a bimetal element secured in saidcasing and having a contact to cooperate with said first mentionedcontact, a second lead wire electrically connected to said bimetalelement, and a cover for the open side of said casing.

3. In a thermostat for heating pads or the like,

a casing of insulating material having an open side, a terminal bar insaid casing, a lead wire through a Wall of said casing and connectedwith said terminal bar, a contact; carried by said terminal bar, saidopposite side of said casing having an elevated portion adjacent one endof said terminal bar, a bimetal element secured thereto and having acontact to cooperate with said first mentioned contact, a second leadwire electrically connected with said second contact and a cover for theopen side of said casing and having opposite notches along its sides,said casing having rabbets receiving the ends of said cover beyond theends of said notches for positioning said cover relative to said casing.

4. A thermostat of the class disclosed comprising a casing of insulatingmaterial having an open side, a terminal bar in said casing adjacent theopposite side thereof, a lead wire connected with said terminal bar, acontact carried by said terminal bar, said opposite side of said casinghaving an elevated wall portion adjacentv one end of said terminal bar,a bimetal element mounted on said elevated wall portion and having acontact to cooperate with said first mentioned contact, a rivet throughsaid elevated wall portion and said bimetal element for securing themtogether, a second lead wire connected with said bimetal element, acover for the open side of said casing, and means surrounding saidcasing and cover and the portions of said lead wires adjacent saidcasing and cover to retain the cover on the casing and secure the leadwires in position relative to the casing.

5. A thermostat of the character described comprising a casing ofinsulating material having an open side, a terminal bar in said casingadjacent the opposite side thereof, a rivet through said opposite sideto retain said terminal bar in position, a contact screw-threaded insaid terminal bar, said opposite side of said casing having an openingin which said contact screw is countersunk, said opposite side havinganother opening, a lead wire extending therethrough and soldered to saidterminal bar, said opposite side of said casing having an elevatedportion, a bimetal element thereon having a contact for cooperation withsaid first contact, a second terminal bar, a rivet through said elevatedportion for retaining said bimetal element and said second terminal barin position thereon, a cover for the open side of said casing, the endsof said casing being rabbeted and said cover being provided with notchedsides whereby the ends or the cover occupy positions in said rabbets andeffect positioning of the cover relative to the casing, a second leadwire soldered to said second terminal bar, said cover having an openingthrough which said last wire extends.

6. A thermostat of the character described comprising a casing having anopen side, a terminal bar in said casing adjacent the opposite sidethereof, a rivet through said opposite side to retain said terminal barin position, a contact carried by said terminal bar, said opposite sideof said casing having an opening, a lead wire extending therethrough andconnected with said terminal bar, said opposite side of said casinghaving an elevated portion, a bimetal element thereon having a contactfor cooperation with said first contact, a rivet through said elevatedportion for retaining said bimetal element in position thereon, a coverfor the open side of said casing, the ends of said casing being rabbetedand said cover being provided with notched sides whereby the ends of thecover 00- cupy positions in said rabbets and effect positioning of thecover relative to the casing, and a second lead wire connected with saidbimetal element, said cover having an opening through which said lastlead wire extends.

7. A thermostat of the character described comprising a casing having anopen side, a terminal bar in said casing adjacent the opposite sidethereof, a rivet through said opposite side to retain said terminal barin position, a contact carried by said terminal bar, said opposite sideof said casing having an opening, a lead wire extending therethrough andconnected with said terminal bar, said opposite side of said casinghaving an elevated portion, a bimetal element thereon having a contactfor cooperation with said first contact, a rivet through said elevatedportion for retaining said bimetal element in position thereon, a coverfor the open side of said casing, the ends of said casing being rabettedand said cover being provided with notched sides whereby the ends of thecover occupy positions in said rabbets and effect positioning of thecover relative to the casing, a second lead wire connected with saidbimetal element, said cover having an opening through which said lastlead wire extends, and a wrapping element around said casing and coverand around the portions of said lead wires adjacent thereto retain thelead wires, casing and cover assembled.

LAWRENCE M. HOWARD.

